[SANTIAGO] The Americas could lose their status as a measles-free region due to the spread of the virus in eleven countries, among which Venezuela accounts for 65 per cent of 2,472 cases confirmed in 2018.

According to a recent epidemiological update (July 20) by the Pan-American Health Organisation (PAHO), Brazil has reported an additional 677 cases — making up 27 per cent of the total for the region — of which 660 were registered in two states bordering Venezuela: Amazonas and Roraima.

All infections involve the measles virus of genotype D8, with a lineage identical to the one identified in Venezuela in 2017.

“The outbreak in Venezuela is still active, also in Brazil,” Desiree Pastor, regional advisor on immunization at the PAHO, tells SciDev.Net, warning that the number could increase as suspected cases are confirmed.

Cases of the disease have also been reported in the United States (91), Colombia (40), Canada (19), Ecuador (17), Argentina (5), Mexico (5), Peru (3), Antigua and Barbuda (1) and Guatemala (1).

In Colombia, 23 of the cases were people who crossed the border from Venezuela, and a further 16 were linked to those cases. In Ecuador, 11 of the 17 people affected are Venezuelans.

“People have not been adequately summoned by the media to vaccinate their children. The government has not indicated where they should go, what vaccines they will apply or to whom,”

José Oletta

“The Americas was the first — and remains the only — region in the world to be declared free of measles in September 2016, after 22 years of mass vaccination targeting children. The last endemic case was reported in 2002 and there has been no sign of transmission of the virus until 2017.

Pastor notes that PAHO has repeatedly warned about the possibility of losing measles-free status. “If a country in the region has sustained transmission of the same genotype of measles virus for 12 months or more, it means that endemic transmission has been restored,” she explains.

This has occurred already, says José Oletta, a member of the Venezuelan Alliance for Health (AVS) and of the Defender of National Epidemiology Network (RDEN), who is also the country’s former Minister of Health (1997-1999).

It is estimated that only 14 per cent of the Yanomami people, such as these children from the Alto Orinoco municipality in Amazonas state, are vaccinated against measles (Credit: Ambar~commonswiki / Wikipedia).

“In July, Venezuela marked one year of transmission of autochthonous [endemic] cases,” he tells SciDev.Net. An outbreak in the state of Bolívar, which was reported in August 2017 by the RDEN and the Venezuelan Public Health Society, in fact, dates back to the first week of July when the initial case was reported. Since then, the disease has spread across the country, putting an end to 10 years without new cases.

In light of this, describing the situation as an “outbreak” is a euphemism, says Oletta — a diplomatic way of referring to what should be considered an epidemic in Venezuela.

According to the former minister, the spread of measles in Venezuela is a result of insufficient immunization coverage over the last decade due to a lack of vaccines; the failure of the government to recognise the epidemic, which means people receive little information about the need to get vaccinated; and the massive displacement of Venezuelans inside and outside the country, which contributes to the rapid spread of the virus on the continent.

Indigenous people living on the border between Venezuela and Brazil — especially the Warao and the Yanomami in Venezuela, and the Yanomami and Ye'kuna in Brazil — are especially concerned because of a high vulnerability to measles and a low vaccination rate of their population.

The graph shows how, since the August 2017 outbreak in the state of Bolívar, measles had spread to all states in Venezuela by January 2018 (Credit: Dr. José Félix Oletta).

PAHO reports that as of early July, there were 126 confirmed cases among Venezuela's Yanomami, including 53 deaths, many of which were among adults.

According to the agency, this “makes necessary preventive or therapeutic interventions different from the rest of the population”. For example, “vaccination of other age groups [not only under five years] in which there is an increase in cases”, says Pastor.

On July 25 the Venezuelan government announced it will implement the second phase of its National Vaccination Plan this month, using “a rapid approach against measles and diphtheria” in conjunction with PAHO.

“The recommendation for Venezuela is to reach a minimum [vaccination] coverage of 95 per cent in the group of children from 6 months to 15 years, to interrupt the circulation of the virus,” says Pastor.

Oletta is pessimistic about this campaign, saying it is poorly designed. “People have not been adequately summoned by the media to vaccinate their children. The government has not indicated where they should go, what vaccines they will apply or to whom,” he points out.